Abstract
Video coding standards employ inter-frame prediction with motion compensation to reduce temporal redundancy. Motion compensation of integer-pel accuracy is not effective for fine movements and the coding efficiency deteriorates. Therefore, motion compensation of quarter-pel accuracy was introduced into H.264/AVC. The one dimensional 6-tap filter is used for the interpolation. However, the values of the filter coefficients are constant regardless of the resolution and the characteristic of the input video. The coding tool called "adaptive interpolation filter" (AIF) was proposed in Video Coding Experts Group (VCEG) of ITU-T. AIF optimizes the filter coefficients on frame basis. However, when the frame is divided into multiple regions where each region has different characteristics, the coding efficiency could improve by optimizing them on region basis. Consequently, we propose the region-based adaptive interpolation filter taking into account the image locality. The simulation results showed that the bit-rate reduction under the same PSNR was about 2% compared to the conventional AIF.
